COBRA rates for a High Deductible Health Plan (HDHP) include the premium for the medical insurance portion. In addition, the following provisions must be made, depending on whether the HDHP deductible is funded by an HSA or HRA.

HSA
The employee keeps their HSA after terminating employment. If the former employee does not keep the HDHP in effect for the remainder of the calendar year and the school funded the entire year, then the former employee would have to claim some of the school’s HSA funding as taxable income. See Partial Year Contributions

HRA
In order to continue to provide the same level of benefit to the terminated employee, the school must continue to administer the HRA and reimburse eligible expenses just as when the employee was employed, as long as they pay for their medical premium. Therefore, the district needs to include the cost (or potential/likely) cost of the HRA reimbursements in the COBRA premiums charged to the employee.